全文获取类型
收费全文 | 927篇 |
免费 | 93篇 |
国内免费 | 185篇 |
专业分类
化学 | 588篇 |
晶体学 | 32篇 |
力学 | 5篇 |
综合类 | 8篇 |
数学 | 253篇 |
物理学 | 319篇 |
出版年
2024年 | 2篇 |
2023年 | 6篇 |
2022年 | 27篇 |
2021年 | 20篇 |
2020年 | 24篇 |
2019年 | 41篇 |
2018年 | 18篇 |
2017年 | 28篇 |
2016年 | 29篇 |
2015年 | 32篇 |
2014年 | 33篇 |
2013年 | 63篇 |
2012年 | 43篇 |
2011年 | 59篇 |
2010年 | 59篇 |
2009年 | 61篇 |
2008年 | 55篇 |
2007年 | 64篇 |
2006年 | 65篇 |
2005年 | 53篇 |
2004年 | 43篇 |
2003年 | 35篇 |
2002年 | 49篇 |
2001年 | 35篇 |
2000年 | 37篇 |
1999年 | 35篇 |
1998年 | 36篇 |
1997年 | 25篇 |
1996年 | 17篇 |
1995年 | 13篇 |
1994年 | 23篇 |
1993年 | 18篇 |
1992年 | 15篇 |
1991年 | 8篇 |
1990年 | 7篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1985年 | 2篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1974年 | 1篇 |
1973年 | 5篇 |
1951年 | 1篇 |
1949年 | 2篇 |
1948年 | 1篇 |
排序方式: 共有1205条查询结果,搜索用时 15 毫秒
111.
Achim Kehrein 《Journal of Pure and Applied Algebra》2006,205(2):279-295
This paper presents several algorithms that compute border bases of a zero-dimensional ideal. The first relates to the FGLM algorithm as it uses a linear basis transformation. In particular, it is able to compute border bases that do not contain a reduced Gröbner basis. The second algorithm is based on a generic algorithm by Bernard Mourrain originally designed for computing an ideal basis that need not be a border basis. Our fully detailed algorithm computes a border basis of a zero-dimensional ideal from a given set of generators. To obtain concrete instructions we appeal to a degree-compatible term ordering σ and hence compute a border basis that contains the reduced σ-Gröbner basis. We show an example in which this computation actually has advantages over Buchberger's algorithm. Moreover, we formulate and prove two optimizations of the Border Basis Algorithm which reduce the dimensions of the linear algebra subproblems. 相似文献
112.
Wavelet sparse approximate inverse preconditioners 总被引:1,自引:0,他引:1
We show how to use wavelet compression ideas to improve the performance of approximate inverse preconditioners. Our main idea
is to first transform the inverse of the coefficient matrix into a wavelet basis, before applying standard approximate inverse
techniques. In this process, smoothness in the entries ofA
−1 are converted into small wavelet coefficients, thus allowing a more efficient approximate inverse approximation. We shall
justify theoretically and numerically that our approach is effective for matrices with smooth inverses.
Supported by grants from ONR: ONR-N00014-92-J-1890, and the Army Research Office: DAAL-03-91-C-0047 (Univ. of Tenn. subcontract
ORA4466.04 Amendment 1 and 2). The first and the third author also acknowledge support from RIACS/NASA Ames NAS 2-96027 and
the Alfred P. Sloan Foundation as Doctoral Dissertation Fellows, respectively.
the work was supported by the Natural Sciences and Engineering Research Council of Canada, the Information Technology Research
Centre (which is funded by the Province of Ontario), and RIACS/NASA Ames NAS 2-96027. 相似文献
113.
Complex symmetric matrices often appear in quantum physics in the solution methods of partial differential equations such as the Schrödinger equation. We have recently introduced a new fast and efficient direct eigensolver for this problem in [4], and reported its performance in the eigenvalue calculation in [3]. In this paper, we further report on some benchmark tests for computing the full and partial eigenspectrum on a variety of super computing machines, i.e., the Cray J-932, the DEC Alfa 8400, and the SGI Power Challenge 8000 and 10000. We observe that in all cases the new algorithm is much faster than codes available in standard state of the art eigensolver packages such as LAPACK. 相似文献
114.
115.
An implementation of the p‐version of the finite element method for solving two‐dimensional linear elliptic problems on a shared‐memory parallel computer
is analyzed. The idea is to partition the problem among the available processors and perform computations corresponding to
different elements in parallel. The parallelization is based on a domain decomposition technique using the Lagrange multipliers.
The numerical experiments carried out on the Sequent system indicate very high performance of the mixed finite element algorithm
in terms of attained speedups.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
116.
Mesoporous molecular sieves Al-MSU-S has been prepared from the precursor of zeolite Y using ionic liquids 1-hexadecane-3-methylimidazolium bromide (CMIMB) as a template in basic medium, which exhibited larger pore diameter, pore volume and surface area than that synthesized using cetyl trimethyl ammonium bromide (CTAB) template. 相似文献
117.
118.
119.
120.
Stig Skelboe 《BIT Numerical Mathematics》1992,32(4):689-701
This paper presents a class of parallel numerical integration methods for stiff systems of ordinary differential equations which can be partitioned into loosely coupled sub-systems. The formulas are called decoupled backward differentiation formulas, and they are derived from the classical formulas by restricting the implicit part to the diagnonal sub-system. With one or several sub-systems allocated to each processor, information only has to be exchanged after completion of a step but not during the solution of the nonlinear algebraic equations.The main emphasis is on the formula of order 1, the decoupled implicit Euler formula. It is proved that this formula even for a wide range of multirate formulations has an asymptotic global error expansion permitting extrapolation. Besides, sufficient conditions for absolute stability are presented. 相似文献